1. Technical Field
This invention generally relates to pressurized containers, and more specifically relates to an inflator for a vehicle protection apparatus.
2. Background Art
Inflatable vehicle restraints such as air bags are used for protecting vehicle occupants during collisions. When the vehicle undergoes a collision a sensor detects the rapid change in motion and provides an electrical signal to activate an inflator, which rapidly expands an air bag to provide a protective cushion of restraint for an occupant in various impact conditions.
Many types of inflators have been disclosed in the art for inflating an inflatable restraint system. One type utilizes a stored compressed gas, which is released to inflate the restraint system. Another type utilizes a combustible gas generating material, such as sodium azide, which upon ignition generates a quantity of hot gas to inflate the restraint. In yet another type, a combination of a compressed stored gas and a combustible material are both used to inflate the restraint. Inflators using combustible gas are often considered unsafe because of the heat that they generate. However, compressed gas inflators have often been unreliable or they have released compressed gas at an excessive rate that causes air bags to injure vehicle occupants.
Therefore, there existed a need to provide a reliable inflator that will inflate a vehicle restraint without generating excess heat. The present invention provides a pressurized container that includes a hollow vessel defining a chamber therein. A housing that is connected to the vessel defines an outlet that is fluidly separated from the chamber by a closure member. A moveable member is seated within and forms a seal with the housing and abuts the closure member. When an initiator is activated, a charge within the initiator is ignited to produce expanding gases that burst a body of the initiator and propel the moveable member through the closure member, thereby fluidly connecting the chamber and the outlet. The moveable member may break through the closure member before the seal with the housing is broken so-that the moveable member acts like a piston.
A pressurized container might include an obstruction partially blocking an outlet path and another initiator that breaks the obstruction when activated, thereby further opening the outlet path.
Also, the chamber might include a first portion and a second portion, wherein an isolator member substantially fluidly separates the first portion and the second portion. A passage fluidly connects the first portion of the chamber and the second portion of the chamber. This dual chamber configuration might be useful where it is desirable to keep a device inflated over a period of time.
The pressurized container might include a main path fluidly connected to the outlet, a first secondary path that connects the main path to the chamber, and a second secondary path that also connects the main path to the chamber. If the pressurized container includes two secondary paths, a first closure member can fluidly separate the outlet from the chamber of the vessel along the first secondary path, and a second closure member can fluidly separate the outlet from the chamber of the vessel along the second secondary path. Activation of a first initiator breaks the first closure member, thereby fluidly connecting the chamber and the outlet along the first secondary path and the main path, and activation of a second initiator breaks the second closure member, thereby fluidly connecting the chamber and the outlet along the second secondary path and the main path. If the pressurized container includes either the first and second secondary paths as described, or the pressurized container includes the obstruction to the outlet path, an initial flow is minimal, and when the obstruction is removed or the second secondary outlet path is opened, then the flow of pressurized gas is increased. In this way, the initial force of an inflatable device such as an air bag is minimized during the initial flow stage, but the flow is substantially increased during the latter flow stage so that the device is rapidly inflated.
The present invention also provides a pressurized container that includes a hollow vessel defining a chamber and a housing connected to the vessel that defines an outlet. The outlet is fluidly separated from the chamber by a closure member, so that activation of an initiator breaks the closure member, thereby fluidly connecting the chamber and the outlet. The vessel and the closure member may be a single unitary member so that the closure member, the vessel, and a plug in the vessel form a sealed barrier around the chamber. Also, the housing and the closure member may be a single unitary member, wherein the housing is inertia welded to the vessel to form the chamber. Having the barrier around the chamber be formed by unitary members provides superior prevention against leakage of compressed gas from the chamber during storage.
The present invention also provides a method of releasing a pressurized fluid from a container. The method includes the steps of breaking a closure member that fluidly separates the pressurized fluid from an outlet of the container, thereby allowing the fluid to escape to the outlet along an outlet path, and breaking an obstruction that is partially blocking the outlet path, thereby further opening the outlet path.